How to teach algebra

Grade 4 to Grade 6

Early algebra uses a letter to stand for an unknown number, then finds its value. An equation like x + 5 = 12 is a balance: whatever you do to one side you must do to the other. Solving means undoing the operations around x using their inverses until x is alone.

How to teach it

1. Start with the balance idea using scales or a bar model, so an equation means both sides are equal, not 'work out the answer'.
2. Begin with a missing number in a box (box + 5 = 12) before swapping the box for a letter.
3. Teach inverse operations: addition undoes subtraction, multiplication undoes division. To solve x + 5 = 12, subtract 5 from both sides to get x = 7.
4. Work steadily up to two steps: for 3x = 12 divide both sides by 3 to get x = 4, then combine with a plus or minus step.
5. Always check by substituting the answer back into the original equation.

Common mistakes

• Treating the equals sign as 'here comes the answer' rather than 'the two sides balance'.
• Changing one side of the equation without doing the same to the other.
• Using the same operation instead of its inverse (adding 5 again instead of subtracting it).
• Reading 3x as 3 followed by x rather than 3 multiplied by x.